People join hands on a coastal levee to remember the victims of the March 11, 2011 earthquake and tsunami, in Miyako city, Iwate Prefecture, Japan. Across Japan, people paused at 2:46 p.m. - the moment the magnitude-9.0 quake struck a year ago - for moments of silence, prayer and reflection.

(AP Photo/Kyodo News)

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Tokyo

A series of earthquakes rattled Tokyo and northeast Japan late Wednesday evening but caused no apparent damage or injury in the same region hit by last year's devastating tsunami.

The strongest tremor, off Hokkaido island, was 6.8 magnitude and caused tidal changes that prompted some communities to issue evacuation orders or tsunami advisories to residents nearest the coast.

A swelling of 20 centimeters (8 inches) was observed in the port of Hachinohe in Aomori, northern Japan, about one hour after the tremor. Smaller changes were reported in several locations on Hokkaido island and Aomori prefecture.

Within about three hours, a magnitude-6.1 quake shook buildings in the capital. It was centered just off the coast of Chiba, east of Tokyo, at a rather shallow 15 kilometers (9 miles) below the sea surface.

Narita International Airport briefly closed runways for inspection but later resumed operation. Several local train services were suspended for safety checks.

There were no abnormalities reported at nuclear power plants after the two earthquakes, operators said. Nearly all of Japan's nuclear plants are offline for safety inspections.

The temblors were considered aftershocks of last year's massive quake, Meteorological Agency official Akira Nagai told a news conference, warning residents to stay away from buildings and plots already loosened by that tremor and the thousands of aftershocks that have followed.

The town of Otsuchi in Iwate prefecture, where more than 800 died in last year's tsunami, issued an evacuation order to coastal households as a precaution after the 6.8 quake, said prefecture disaster management official Shinichi Motoyama. No damage or injury was reported, he said.